"A stupid person can make only certain, limited types of errors; the mistakes open to a clever fellow are far broader. But to the one who knows how smart he is compared to everyone else, the possibilities for true idiocy are boundless."
One thing that is slightly more frustrating is saying “What dumbass wrote this code? How did this ever work?” And then looking at git blame and realizing the dumbass is year-ago you. (Or even five years ago you.)